1. Field of the Invention
This invention relates to a programmable sewing machine having a function of delivering a plurality of option output signals for controlling optional devices optionally provided for the sewing machine.
2. Description of the Related Art
Various types of sewing machines such as lock stitch sewing machines or embroidery machines for industrial use are used in tailors, dressmakers or the like. They demand to additionally provide various optional devices on the sewing machines. When the optional devices are added to the sewing machines, the efficiency in the sewing work and the quality of products can be improved according to the changes in the type and size of a workpiece cloth and the changes in the contents of the sewing operation.
The prior art has proposed various types of programmable electronic sewing machines having a function of delivering option output signals for operating the optional devices individually. For example, Japanese Examined Patent Publication No. 6-59351 (1994) and Japanese Unexamined Patent Publication No. 8-280957 (1996) disclose sewing machines in which sewing data used for the sewing of a workpiece cloth contains control data for delivery of option output signals for controlling the optional devices, respectively. In the disclosed sewing machines, the control data is read during execution of the sewing operation so that one or more designated optional devices are controlled during the sewing operation on the basis of the read control data. Consequently, the optional devices can be operated individually.
The prior art has further provided a sewing machine provided with a simplified sequential control. FIG. 16 shows four sequences 1 to 4 of the sewing machine. The sequences can be started on different starting conditions respectively. Four output signals are sequentially delivered in each of the sequences 1 to 4. The control in each of the sequences 1 to 4 is started on the condition of a previously set operating state of the sewing machine selected from those of a plurality of basic operating sections of the sewing machine. For example, the operating states of the basic operating sections include those when the sewing machine has returned to a home position, when a start switch has been operated, and when a thread has been cut off or removed.
The control of the sequence 1 is started when the starting condition thereof is fulfilled, for example. First, an option output 0 is turned on or off when the starting condition thereof is fulfilled. An option output 1 is then turned on or off when the starting condition thereof is fulfilled. Subsequently, option outputs 2 and 3 are sequentially delivered. The outputs are sequentially delivered in each of the other sequences 2 to 4 in the same manner as described above. Thus, sixteen option outputs 0 to F are delivered as the result of control of the four sequences.
According to the sewing machines disclosed in the above-referenced Japanese patent publications, the control data need to be stored at predetermined locations of the sewing data respectively. For this purpose, the control data are incorporated into the sewing data according to the number of the optional devices, the number of times of operation of each optional device, etc. in an editing process executed after origination of the sewing data. This results in complication of the sewing data originating and editing processes. Furthermore, the optional devices can be operated only during execution of the sewing operation. This results in another problem that the optional devices cannot be operated while the sewing is not executed.
In the conventional sewing machine with the simplified sequential control, the starting condition for each sequence is limited to a single operating state previously selected from those of the plurality of basic operating sections of the sewing machine. Accordingly, when an option output signal is desired to be delivered to operate the same optional device on a plurality of starting conditions, each sequence is appropriated or occupied by the plurality of starting conditions. Since this reduces the number of remaining sequences, the number of option output signals capable of being delivered is reduced. Furthermore, since the starting condition for each sequence is limited as described above, one option output signal cannot be delivered in synchronization with delivery of another option output signal in a different sequence. Additionally, the delivering condition for each of the four option output signals delivered from each sequence is restricted so as to be set in connection with the preceding option output. This results in difficulty in setting conditions for timely delivering each of a plurality of option outputs.
A stacker is sometimes provided optionally for moving sewn products to one side of the sewing machine to stack them. The stacker is proposed to be operated when a cloth presser of the sewing machine has been ascended. In this case, "ascent of cloth presser" may be set as a starting condition for the sequence. However, the presser bar is ascended not only when the sewing is finished but when a workpiece cloth is set at a sewing location prior to the start of the sewing. This would result in malfunction of the stacker when the workpiece cloth is set.